"A liquid water layer or pocket in contact with the rock, which is deep below Enceladus' surface, will acquire sodium from the rock - essentially leaching the rock," he says.

'the easy northwest ridge' was described rock by rock in the battered guidebook that Carlo carried in his pocket, along with the wire I mentioned.

They created a geological pocket 900 feet long and up to 238 feet wide in the dome by pumping water into it to dissolve the rock salt.